The present invention pertains to an apparatus for applying fluid to a substrate which is movable relative to the apparatus, in particular for applying adhesive to various substrates.
Dispensing apparatus relevant to this invention are often referred to as applicator heads, and are used in various areas of industry in order to apply adhesives or other fluids to the surface of various substrates such as films, foils, or packaging materials. The applicator head may be mounted on a frame, and the substrate is typically moved past the applicator head by a transport device. In operation, the fluid may discharge from an elongate outlet aperture of a slot.
JP 05200346 (patent abstracts of Japan) describes a slotted nozzle coating apparatus with a slot for emitting coating material. The width of the slot can be adjusted on both sides by introducing so-called stoppers.
To vary the length of the slot in the slotted nozzle assembly and thereby vary the width of adhesive or other fluid application, it has been suggested that movable stoppers be placed on both lateral end sections of the slot, which can be shifted in the slot and held in various positions which limit the slot laterally. In this way the width of fluid application can be reduced on both sides, starting from a maximum fluid application width.
There is still a need for a fluid dispensing apparatus of this general type which has a more efficient and easily used design to provide for variation of the application width and adaptation to various application conditions.
The invention uses a simple design not only to enable varying the length of the slot in the slotted nozzle assembly, but also to shift the entire application head if needed, in order to be able to align the application head precisely in reference to various substrates which are transported past it. The apparatus in accordance with the invention has several adjustment options. By sliding the entire main body in the direction of the longitudinal axis of the slot and at the same time shifting the stopper in the same direction, the width of application remains constant and the slotted nozzle assembly is shifted together with the application head relative to a substrate while the length of the slot remains constant, so that the width of application remains the same and the slotted nozzle assembly can be positioned exactly with respect to the substrate. Alternatively, the slotted nozzle assembly can be shifted by using a guiding and adjusting device, while the stopper which is positioned movably in the slot and seals it laterally does not change its position, relative to a fixed-position frame of a production facility, but only changes its position relative to the slotted nozzle assembly of the application head. The length of the slot is reduced in this case and one lateral margin of the slot changes its position relative to the substrate. Alternatively, the stopper which is movable within the slot can be moved in the slot with the help of an adjusting device, while the main body remains stationary relative to a fixed-position frame, so that the length of the slot is varied and one lateral end section of the slot changes its position while the other end section of the slot retains its position.
The apparatus in accordance with the invention thus makes much more varied adjustment of the width of the slot and position of the slot possible relative to a substrate, compared to the state of technology. The two lateral margins of the slot can be varied and the entire slotted nozzle assembly can be moved.
A preferred implementation of the invention is distinguished by the fact that the guiding and adjusting device has several linear guides, preferably having rollers, so that simple shifting is possible with little force and a rigid arrangement of the application head is assured when it is in its fixed state.
In an especially preferred way, the guiding and adjusting device is designed with a rotatable threaded spindle and a threaded piece located on the main body and engaging the threaded spindle, so that reliable and precise adjustment is possible with simple design. Alternatively, a ball screw spindle could be used. It is useful for the threaded spindle to be coupled with a hand wheel for manually moving the main body, whereby simple and precise repositioning is possible.
According to an alternative preferred implementation, the stopper, which can move in the slot, is rigidly connected to a piston which is positioned movably and sealed in a distribution passage which communicates with the slot. It is useful for the stopper and the piston to be movable by means of a shared slot adjusting device. With the help of the piston which is positioned movably in the distribution passage and the stopper, the distribution passage is varied laterallyxe2x80x94together with the slot length. Furthermore, fluid is fully squeezed out of the distribution passage, so that no fluid residues collect, a factor which is especially important when processing adhesives. Furthermore, with the help of the piston and the stopper the apparatus can be cleaned and adhesive can be pressed out of the slot and the distribution passage when operation is interrupted for an extended time, so that no hardening of the adhesive occurs.
A refinement of the invention is designed with the adjusting device having a threaded spindle mounted so that it can turn, and a threaded sleeve which is rigidly connected to the piston and engages the threaded sleeve. Preferably the threaded spindle of the adjusting device is coupled with a hand wheel for manual adjustment.
Especially simple handling of the application head in accordance with the invention is achieved by having the hand wheel of the guiding and adjusting device and the hand wheel of the slot adjusting device positioned parallel, side-by-side on one side relative to the main body and the threaded spindles, since the guiding and adjusting device for the main body and the slot adjusting device can be operated from one side, even while the device is in operation during application.
According to a refinement there is a substrate guiding device, having a frame which can be caused to rotate on the main body by means of a pneumatic cylinder and two elongated guide elements mounted on the frame parallel to the slot, and the guide elements for their part are arranged so that they can be rotated or fixed jointly relative to the frame.
Because the frame can be rotated relative to the main body on the one hand, and because on the other hand the two guide elements which are in contact with the substrate are arranged so that they can be fixed or rotated relative to the frame, in operation the substrate is positioned optimally relative to the outlet aperture of the slot in the slotted nozzle assembly and guided past it so that optimal application of fluid is achieved. In an especially simple design, the guide elements are designed as guide rods with a polished surface. Alternatively, the guide elements could be constructed as rotatable shafts in order to reduce the friction.